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Nasrin Sotoudeh, a prominent Iranian human rights advocate, was among several prisoners released Wednesday from a Tehran prison where she had been jailed since 2010.

"I'm glad, but I'm worried for my friends in prison," she told CNN's Christiane Amanpour in a telephone interview soon after her release, citing other political and human rights activists who remain in prison.

Sotoudeh said authorities at the notorious Evin Prison initially told her she would be allowed out on a short break. They then put her into a car.

It was only after she had been driven out of the gates that one of the prison heads told her, "No, you are free forever, and that's why we're taking you home," she said.

The prison in the capital's northwest section had been her home since she was convicted of acting against national security and other charges related to her work in defending Iranians who were detained after the 2009 elections, which returned Mahmoud Ahmadinejad to the presidency. She was reunited with her husband, Reza Khandan, and her two children.

As a prisoner, Sotoudeh had gone on a hunger strike to express her anger over the effect that her 11-year sentence was having on her family, she said. The term included five years for "acting against national security;" another five years for not wearing a hijab -- a head covering worn by Muslim women -- during a videotaped message; and an additional year for "propaganda against the regime," the International Campaign for Human Rights in Iran reported.

Sotoudeh's release comes just days before world leaders, including Iranian President Hassan Rouhani, attend the U.N. General Assembly meeting in New York. U.N. Secretary-General Ban Ki-moon had urged Iran to free jailed opposition leaders, journalists and human rights activists in 2012.

In 2011, a U.S. State Department spokesman called Sotoudeh "a strong voice for rule of law and justice in Iran." Washington praised her release and challenged Rouhani to follow up on it by freeing "all prisoners of conscience," State Department spokeswoman Marie Harf said.

"President Rouhani pledged repeatedly during his campaign to restore and expand freedoms for all Iranians, and called for expanded political and social freedoms, including freedom of expression," Harf said in a written statement. "In the months ahead, we hope he will continue to keep his promises to the Iranian people."

Sotoudeh told CNN she expected to be allowed to continue practicing as a lawyer after her release. Asked if she considered it to be a new day for Iran, she noted that "many political prisoners" remain in jail. "But I hope that this will be a new day," she said.

In an earlier telephone interview, Khandan said his wife, who is a lawyer, had another three years of her sentence remaining and he had not been told whether her release was final.

But Sotoudeh said that her freedom was not temporary. "Free forever," she said.

Sotoudeh was the attorney for Arash Rahmanipour, one of two men executed by the Islamic republic in early 2010. He was accused of being an enemy of God and belonging to a banned opposition group.

In 2012, she shared the European Parliament's Sakharov Prize for Human Rights.